Text-to-speech API limits: when you hit one
4 provider limits with the provider's own sentence and check date. The link in each section gives the verdicts at twice a typical monthly workload.
Cartesia: Too many requests at once
Calls above the concurrency cap wait or are refused.
Free $0 /mo Start free Pro $5 /mo Select Pro Startup $49 /mo Select Startup Scale $299 /mo Select Scale Enterprise Custom Contact us Text to Speech Sonic-3.6
Source: cartesia.ai/pricing
Concurrent requests 2 3 5 15 Custom
Source: cartesia.ai/pricing
Checked 2026-11-11
Plans that clear it: Inworld Creator (20 at once); Inworld Builder (100 at once); Inworld Developer (300 at once).
Inworld: Too many requests at once
Calls above the concurrency cap wait or are refused.
- On-Demand: 10 at once
- Creator: 20 at once
- Builder: 100 at once
- Developer: 300 at once
- Growth: 1000 at once
| Concurrent sessions | 10 | 20 | 100 | 300 | 1,000 | Custom |
Source: docs.inworld.ai/portal/billing.md
Checked 2026-11-11
MiniMax: Requests are rejected with 429
A request rate above the limit is refused.
- Audio Subscription Pro: 200 requests per minute
- Audio Subscription Starter: 10 requests per minute
- Audio Subscription Business: 800 requests per minute
- Audio Subscription Standard: 50 requests per minute
- Audio Subscription Scale: 500 requests per minute
• RPM: 200
Source: platform.minimax.io/docs/pricing/overview
• RPM: 10
Source: platform.minimax.io/docs/pricing/overview
• RPM: 800
Source: platform.minimax.io/docs/pricing/overview
Checked 2026-11-11
Murf: Too many requests at once
Calls above the concurrency cap wait or are refused.
- Pay as you go: 5 at once
- Free Trial: 5 at once
5 for US-East; 2 for global and regional endpoints
Source: murf.ai/api/docs/resources/rate-limits.md
5 concurrent requests
Source: murf.ai/api/assets/usePricingPlansInfo-Dwjn18Vg.js
Checked 2026-11-11
Plans that clear it: Inworld On-Demand (10 at once); Cartesia Scale (15 at once); Inworld Creator (20 at once).